initial commit

shaders/grid_v.glsl

@@ -0,0 +1,27 @@
+#version 330 core
+out vec3 nearPoint;
+out vec3 farPoint;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+// Grid position are in xy clipped space
+vec3 gridPlane[6] = vec3[](
+    vec3(1, 1, 0), vec3(-1, -1, 0), vec3(-1, 1, 0),
+    vec3(-1, -1, 0), vec3(1, 1, 0), vec3(1, -1, 0)
+);
+
+vec3 UnprojectPoint(float x, float y, float z, mat4 v, mat4 proj) {
+    mat4 viewInv = inverse(v);
+    mat4 projInv = inverse(proj);
+    vec4 unprojectedPoint =  viewInv * projInv * vec4(x, y, z, 1.0);
+    return unprojectedPoint.xyz / unprojectedPoint.w;
+}
+
+void main() {
+    vec3 p = gridPlane[gl_VertexID].xyz;
+    nearPoint = UnprojectPoint(p.x, p.y, 0.0, view, projection).xyz; // unprojecting on the near plane
+    farPoint = UnprojectPoint(p.x, p.y, 1.0, view, projection).xyz; // unprojecting on the far plane
+    gl_Position = vec4(p, 1.0); // using directly the clipped coordinates
+}
+